A Learning Process Simulator for Fluidized Bed Dryers Application to Bentonite Drying

A fluid bed dryer simulator was developed under Excel 5 wlth Visual Basic for Applications environment The simulator iS based on a mathematical model describing heat and mass transfer in the dryer. The total model incorporates empirical models for the Drying Constant and the Residence Time. These empirical models are crucial in the total model efficiency. Thus a procedure for updating the parameters of the empirical models is provided. This procedure constitutes the 'learnhg' property of the simulator. Two databases are Supplied. The first contains laboratory drying data and it is used for tuning the Drying Constant empirical model. The second contains industrial drying data from the real operation of the dryer, and it is used for tuning the Residence Time empirical model. The experience from the industrial application of the simulator proved that the simulator is a powerful tool for flexible operation of an industrial dryer. This paper is presents the total mathematical model of the dryer, the learning concept, and the databases, including useful information concerning the drying kinetics of bentonite. A simulator outline is presented and typical capabilities and uses are briefly described. A case study for flexible operation of an industrial dryer is discussed.     

顶喷流化床中干燥过程研究

本文对用于造粒和包涂过程的顶喷流化床内的干燥过程进行了较为详细的实验和理论研究。从传质传热过程中分析可知，床层可分为三段。影响生产能力的最大允许喷淋速度受流化空气流量和入口温度影响最大。     

Fluidized Bed Air Drying: Experimental Study and Model Development

The presented study describes the processes and mechanisms of batch fluidized bed drying. The influencing factors of hot air drying are theoretically and experimentally examined, in order to present the relations between temperature and humidity profiles and all other drying parameters. A physical model is presented to facilitate the calculation of the drying processes under defined conditions. Three succeeding drying stages are therefore modeled. Mass and energy balances including all components taking part in the process are formulated. The model clarities the drying process under the assumption of pure heat transfer mechanisms. It does not contain adaptive parameters and takes into account an inactive bypass fraction of the fluidization and drying medium. The evaluation of the model was successful for two fluidized bed plants with nominal widths of 100 mm and 400 mm. The experiments showed sufficient accuracy and transferability of the model to equipment of application‐oriented dimensions.     

氯化聚乙烯间歇式气流流化床组合干燥新工艺

根据氯化聚乙烯的干燥特性,开发了一种新型间歇式气流流化床组合干燥工艺,产品质量好,环保效果好。     

新型己二酸干燥设备的应用

主要介绍了在己二酸干燥中埋管流化床工艺上的改进,针对己二酸的物料特性,设计出适合己二酸干燥的埋管流化床,并成功应用于生产。     

Multiresolution Analysis of a Drying Process in a Rotating-Distributor Fluidized Bed

Humidity and temperature measurements, together with pressure fluctuation signals, were employed to analyze a drying process in a lab-scale bubbling fluidized bed. The experimental facility was equipped with a rotating distributor. The operational conditions reported in sludge, paste, and granular drying processes were reproduced using silica sand as wet material and as inert medium. Experiments were performed by changing the bed aspect ratio and the water-sand content in the bed operated at ambient conditions. Four drying periods were found when analyzing humidity and temperature signals. The multi-resolution approach of the pressure fluctuation signals showed the effect of the sample drop over the bed surface on the fluidization conditions, by relating the drying periods with the bed dynamics. The drying process can affect the low- and high-frequency details of the pressure signal when the bed state changes towards defluidization, or just the high-frequency detail if the bed was at the maldistributed regime. The drying conditions needed to use the pressure signals to control the drying process are defined by means of a statistical monitoring approach. A comparison between the static and the rotating distributor tests showed clear benefits for the operation with the rotating distributor for shallow and deep beds. When the distributor was rotating, the average improvement of the drying rate was 11%, whereas the drying time was reduced by 40% for the tests of the maldistributed and defluidized regimes.     

Stepwise Change of Operating Pressure in Vacuum Fluidized Bed Drying: An Experimental Study

Vacuum‐fluidized bed drying experiments were carried out with porous as well as compact particles, employing distinct operating pressures in two periods of drying, such that the combination of the effects of decrease in the transport capacity of the exterior medium and the enhancement of the internal diffusivity results in favour of the drying process. In a variety of operating conditions, it was observed that in the case of porous particles, increasing the operating pressure during the decreasing drying rate period, after applying a vacuum pressure in the constant drying rate period results in a lower final particle humidity.     

干燥过程特性和干燥技术的研究策略

从对干燥过程特性认识的进展，变温干燥方法对提高干燥过程速率及防止降速干燥阶段物料变质的作用、干燥过程强化、节能和产品质量之间的关系，干燥理论和干燥过程模型化的进展及存在困难，以及近年来国际上对干燥技术的关注重点等方面为依据对我国的干燥技术研究策略作了简要的评述。     

流化床干化法在污水处理厂污泥处置中的应用

针对大伙房水库上游污水处理厂污泥处理过程中存在的问题,提出采用流化床污泥干化法对污水厂脱水后的污泥进一步处理,实现减量和无害化。文中给出了详细的工艺过程和参数,对污泥干化工程的实施有一定的参考价值。     

己二酸生产中沸腾床干燥和气流干燥工艺性能比较

在目前己二酸生产中,用于固体物料干燥的代表性工艺是气流式及沸腾床式2种,对2种T艺在己二酸干燥中应用进行了综合性比较。     

酒精污泥在内热式振动流化床中的干燥特性研究

以干污泥颗粒为惰性粒子,采用内热式振动流化床对酒精污泥进行了干燥实验,考察了流化气速、进气温度、振动频率和内加热功率对污泥干燥特性的影响,分析了污泥湿含量和干燥速率的变化规律。结果表明,干燥速率随着流化气速、进气温度和内加热功率的增加而增加,随着振动频率增加呈先增长后降低的趋势。适度提高流化气速、进气温度、振动频率和内加热功率可以降低最终湿含量。将干燥过程分为降速I段和降速Ⅱ段,根据扩散传质理论,建立了内热式振动流化床中污泥干燥的数学模型,模型计算值和实测值的误差在20%以内,符合较好。实验结果为酒精污泥干燥过程的工业设计和操作提供了实验依据。     

Optimization of Fluidized Bed Drying Process of Green Peas Using Response Surface Methodology

The fluidized bed drying process of green peas was optimized using the response surface methodology for the process variables: drying air temperature (60–100°C), tempering time (0–60 min), pretreatment, and mass per unit area (6.3–9.5 g/cm²). The green peas were pretreated by pricking, hot water blanching, or chemical blanching. Product quality parameters such as rehydration ratio, color, texture, and appearance were determined and analyzed. Second-order polynomial equations, containing all the process variables, were used to model the measured process and product qualities. Rehydration ratio was influenced mostly by pretreatment followed by tempering time, temperature, and mass per unit area. Pretreatment and mass per unit area significantly affected color and texture. Higher levels of temperature and lower levels of tempering time and mass per unit area increased the rehydration ratio. The optimum process conditions were derived by using the contour plots on the rehydration ratio and sensory scores generated by the second-order polynomials. Optimum conditions of 79.4°C drying air temperature, 35.8-min tempering time, pretreatment of the once pricked peas with chemical blanching in a solution of 2.5% NaCl and 0.1% NaHCO₃, and mass per unit area of 6.8 g/cm² were recommended for the fluidized bed drying of green peas. At these conditions the rehydration ratio was 3.49.     

下饲煤技术在碳酸钙生产中的应用

介绍了下饲煤技术的原理、优点及其在中小碳酸钙厂的应用,该技术无论从提高经济效益还是从环保角度都极具推广价值。     

糊用聚氯乙烯树脂的喷雾干燥技术

近几年我国PVC产量提高迅速,受市场及国家宏观调控,悬浮法生产PVC近于饱和,而糊用PVC市场需求较大,因此,一些企业准备扩产或对原装置进行改造。现对糊用PVC装置中的干燥技术作一简介。     

流化床反应器过程强化技术

Fluidized beds enable good solids mixing, high rates of heat and mass transfer, and large throughputs, but there remain issues related to fluidization quality and scale-up. In this work I review modification techniques for fluidized beds from the perspective of the principles of process intensification (PI), that is, effective bubbling sup-pression and elutriation control. These techniques are further refined into (1) design factors, e.g. modifying the bed configuration, or the application of internal and external forces, and (2) operational factors, including altering the particle properties (e.g. size, density, surface area) and fluidizing gas properties (e.g. density, viscosity, or velocity). As far as two proposed PI principles are concerned, our review suggests that it ought to be possible to gain improve-ments of between 2 and 4 times over conventional fluidized bed designs by the application of these techniques.     

A Quasi-stationary Approach to Drying Kinetics of Fluidized Particulate Materials

A modified quasi-stationary method has been proposed to describe drying kinetics of particulate materials dried in convective dryers with active hydrodynamic regimes. Both our own results and literature data were used. These include sliced celery, cranberry, diced carrot, wheat and polystyrene granules dried in four types of dryers: pulsed fluid bed dryer, fluid bed dryer with a mixer, spouted bed dryer with a draft tube, and vortex dryer. The method was validated by comparing experimental data with results of modeling in terms of a reduced moisture content and material temperature. A new form of the generalized drying curve has been proposed with the reduced time and the index of hydrodynamic intensity as parameters. The equations developed can be used to calculate the total drying time and determine the temporal variation of the moisture content and material temperature.     

基于LS-SVM和Pensim仿真平台的青霉素发酵过程建模

从青霉素发酵过程仿真平台(Pensim)得到的结果作为出发点,采用最小二乘支持向量机(LS-SVM)对青霉素发酵过程进行建模研究。分别研究丁利用溶解氧浓度、排气二氧化碳浓度等变量对青霉素产物浓度、菌体浓度和底物浓度等重要过程变量的建模问题,在3种不同的仿真条件下分别建立了相应的在线预报模型,并对其进行了分析和比较。基于 Pensim 的仿真结果表明采用 LS-SVM 方法所建立的在线预报模型均具有良好的预测精度,对后续发酵过程的控制和优化能起到一定的参考作用。     

褐煤干燥成型工艺技术综述

褐煤干燥成型技术是将成本低廉的富含水分的褐煤在一定温度下经脱水后转化成为具有类似烟煤性质的提质煤。提质后的褐煤更有利于综合利用、运输和贮存,且具有可观的经济价值。介绍了国外7种褐煤干燥工艺技术和褐煤热压成型技术;着重论述了管式间接干燥工艺和高压热压成型工艺的干燥过程、成型过程、工艺特点及优缺点;通过工艺设计数据、物料衡算基准和关键设备配置,例举了褐煤干燥成型工艺设计应用实例;分析和论证了褐煤成型过程的性能保证和安全性保障。对褐煤干燥成型生产装置进行了技术经济评价,结果表明：建设1套百万吨级的褐煤干燥成型工厂,其建设投资约为3.8亿元,型煤加工成本约为60元/t。     

Measurement Techniques to Monitor and Control Fluidization Quality in Fluidized Bed Dryers: A Review

Fluidized bed dryers (FBD) are commonly employed in many industries to dry particulate solids. FBDs provide good solids mixing, high rates of heat and mass transfer, and relative ease of material handling. For efficient operation, it is important to be able to monitor and control the fluidization regime, particle size distribution (PSD), moisture content, and bulk density as well as product chemical properties. This review provides an overview of the trends in the application of different experimental techniques to monitor and control the hydrodynamic conditions of FBDs which influence the particle physiochemical properties. This review covers a wide range of measurement techniques, including infrared moisture sensor (IR), near infrared (NIR) spectroscopy, analysis of pressure fluctuations, optical imaging techniques, acoustic emission (AE), electrical capacitance tomography (ECT), spatial filter velocimetry (SFV), Raman spectroscopy, focused beam reflectance measurement (FBRM), microwave resonance technology (MRT), triboelectric probes, positron emission particle tracking (PEPT), and some novel techniques for monitoring and control of FBDs. The present review summarizes the use of the diverse techniques and outlines their merits and limitations. Prospects for future research in this area are also identified. The measurement techniques can be used for research, development, and operation of fluidized bed equipment used in non-drying applications as well.     

ADC发泡剂干燥工艺的改进

阐述我国目前ＡＤＣ发泡剂干燥工艺的过程,剖析当前生产技术中存在的问题,并提出改进措施。